Moving Coil
cartridges are plentiful and more
affordable today than ever, however
designing a good phono preamp capable
of amplifying the very low mc signals
can be a real challenge and in fact,
very difficult if designing with vacuum
tubes. We all love the sound of
tubes but obtaining enough gain
(60-70dB) from a minimalist two stage
preamp design is hard to accomplish
without sacrificing noise and
bandwidth. Add a third gain stage, or
head amp, as some designers do, and
you've just introduced more noise and
distortion. There's nothing worse
than a humming phono pre with so much
tube hiss that it sounds like you have
an ocean right in your living
room!
The
solution? Add a good quality step
up transformer to the front end of a
medium gain phono preamp! It's
not quite so difficult to design a two
stage phono pre with 40-50dB of gain so
the addition of a step up transformer's
10-25dB of boost easily solves the gain
issue without the addition of a noise
component.
The diagram
below outlines a typical application
using our new 'PUP Moving Coil kit. The
step up transformers are inserted
between the moving coil cartridge and a
medium
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- FEATURES -
- 25dB of
Gain
Enough
gain to bring all moving coil cartridge
outputs up to moving magnet
levels.
-
Nickel Laminate
Construction
Nickel provides the best material for
this transformer design. You can
hear the difference!
- Copper
and Silver Wire Coils
Our basic kit features copper wound
step up transformers or you can upgrade
to the ultimate with Electra-Print's
all silver wound coils.
- Ground Lift
Switch
The inclusion
of a ground lift switch helps to
minimize system ground loops.
- Small Compact
Size
Measuring
just 1.75" x 4.0" x 4.0" (44mm x
102mm x 102mm)
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'PUP is designed to minimize noise pick
up. A special wiring technique is
used to minimize ground induced hum.
The transformer leads are kept very
short and soldered directly to the RCA
connectors. And the aluminum case
is grounded to increase the amount of
shielding. We also incorporate a
toggle switch that allows you to
connect or float the primary side
ground of the transformer thereby
providing another weapon against
potential ground noise. Of course
we use a super high quality
hermetically sealed switch featuring
all silver contacts.
Features:
The heart of 'PUP is of course the
step up transformers. 'PUP uses
transformers manufactured by
Electra-Print Audio renowned for
winding some of the best transformers
in the world! These transformers
feature nickel laminates and your
choice of high purity copper or all
silver coils. The 'PUP
transformers provide a 1:18 step up in
voltage, for a gain of 25dB, and are
well suited for moving coil cartridges
requiring a load in the 30-200 ohm
range.
We house the transformers in an
ultra-compact enclosure. In fact
it's so compact you might want to bolt
it to your turntable plinth or an
equipment rack shelf. We include a set
of mounting flanges (shown below) that
make it easy to attach the 'PUP just
about anywhere.
It's all quite simple really, and our
easy-to-follow assembly instructions
will not only insure proper
construction but it will have you
listening to music in no time at
all.
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Medium gain moving magnet type
phono preamps typically have a 47kohm
input impedance. Our step up
transformer will reduce this number
such that the moving coil cartridge
sees an impedance of approximately 150
ohms. Most moving coil cartridges
will be quite happy with this load,
however if you feel it is important to
match it exactly, a resistor can be
paralleled to the output of the step up
transformer thereby reflecting a nearly
exact load impedance required by your
cartridge. But let us do the math
for you. Just tell us the
recommended load given by the
manufacturer of your cartridge along
with the input impedance of your phono
preamp and we'll do the rest.
'PUP is available in
kit form or factory assembled by
Welborne Labs
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